When drilling into a surface of the aforesaid kind, i.e. normally indoors, two troublesome problems occur. When a dry-drilling operation is used, the drill dust and cuttings pervade the surroundings, to penetrate and settle on almost all conceivable locations. When a coolant or flushing liquid, normally water, is used in conjunction with a drilling operation, this coolant or flushing liquid in most cases being introduced through the drill, serious difficulties are encountered in preventing an undesirable and uncontrollable flow of liquid from the drilled hole, especially in the case of a hole drilled in a vertical wall or a ceiling. Various "open" arrangements comprising a suction conduit applied to remove the outflowing liquid by suction normally provide a clearly unsatisfactory result.
It has been suggested that one should use "back suction", i.e. that there is used a hollow drill and that drill cuttings and/or liquid (it is assumed that the latter is supplied in a controlled manner externally of the drill) is, or are, removed by suction through the hollow drill, with the aid of dry or wet suction means connected through a swivel coupling. A controlled supply of liquid is very difficult to achieve even in this case, however, when the hole is drilled laterally into a vertical wall or upwardly into a ceiling, for example.
One method of attempting to master this problem is to place around the drill an elastic annular element which seals against both the drill and the surface being drilled and which is displaced progressively along the drill as said drill penetrates into the surface. The liquid is fed through a separate channel into the wedge-shaped sealed space defined by the elastic annular element, at precisely that place where the drill enters the aforesaid surface. It would be possible also to use such an elastic annular element in the absence of back suction, i.e. it would be possible to supply the flushing liquid through the interior of the drill and to remove the liquid by suction through said wedge-shaped space and said channel. An example of such an annular seal is found in DE No. A1 30 49 268.
Sealing rings of the aforesaid kind, however, have been found relatively unsuitable in use; difficulties can be experienced in obtaining a satisfactory seal; the displacement of the sealing ring on the drill can lead to problems; different drill sizes require different sizes of sealing ring etc.; durability and ease of handling are not so good.
For the purpose of collecting primarily drill cuttings when dry-drilling, it is also known to use a cup-shaped device which is pressed sealingly against the underlying surface as drilling takes place, the drill passing through a suitably adapted hole in the cup bottom, through the cup space and into said surface, e.g. a wall. The device is held by hand and is hence encumbered with obvious functional limitations and drawbacks. Devices of this kind seem to have limited use, and then primarily with drills of relatively small diameter.